entek/lyping/App/LinkSDK/components/ota/ota_md5.o /home/alientek/lyping/App/LinkSDK/components/ota/aiot_ota_api.o -lpthread
hello.o: file not recognized: File format not recognized
collect2: error: ld returned 1 exit status
Makefile:22: recipe for target ‘main’ failed
make: *** [main] Error 1

原因：最初使用X86编译器，更换为ARM的编译，有部分文件为X86编译器

解决办法：make clean

清理后再编译。